1. Field of the Invention
The present invention is directed to construction techniques involving anchoring systems.
2. Description of the Related Art
A building is subject to extreme forces from nature. High winds and earthquakes, in particular, cause forces that place considerable strain on the stability of a building. Proper distribution of these forces is critical to ensure the stability of a structure. At the core of building stability is the building's foundation and thus securing the walls of a building to the foundation greatly improves structural performance.
In constructions such as residences and small buildings, a lateral bracing system typically includes vertical studs spaced from each other and affixed to horizontal top and bottom plates. The bottom plate is typically anchored to the floor diaphragm or foundation. The bracing system typically further includes sheathing affixed to the studs, upper plate and/or lower plate to increase structural response to lateral forces. The sheathing used is generally oriented strand board (OSB) or plywood, but fiberboard, particleboard and drywall (gypsum board) are also used. Alternatively or additionally, light-frame construction wall sections may include prefabricated shearwall sections, which can be positioned between the vertical studs and affixed to the studs and the top and bottom connecting plates. The sheathing or prefabricated panels can also be placed adjacent door and window frames to improve the response to lateral forces at these locations.
Shearwalls were developed to counteract the potentially devastating effects of natural phenomena such as seismic activity, high winds, floods and snow loads on the structural integrity of light-framed constructions. Prior to shearwalls and lateral bracing systems, lateral forces generated during these natural phenomena often caused the top portion of a wall to move laterally with respect to the bottom portion of the wall, which movement could result in structural failure of the wall and, in some instances, collapse of the building. Shearwalls within wall sections of light-framed constructions provide lateral stability and allow the lateral forces in the wall sections to be transmitted through the shearwalls between the upper portions of the wall and the floor diaphragm or foundation of the building where they are dissipated without structural effect on the wall or building.
A conventional prefabricated shearwall is anchored to an anchor bolt which extends from a foundation. Anchor bolts in the foundation may also be used with hold-downs in non-prefabricated environments. Much of the time, a concrete contractor places anchor bolts in a foundation to secure these shearwall elements. These bolts must be placed at specific locations in order to mate with the shearwall elements. If the contractor misplaces the anchor bolts, this can create a problem since it will not be recognized until the concrete sets. Since the bolts are critical to ensuring the performance of the shearwall unit, misplacement can be costly.
Hence, proper performance of the shearwall is dependent, at least in part, on the structural integrity of the foundation. Other anchor fasteners could also benefit from correct positioning in the foundation, including mudsill anchors.
It is well known in the construction and building industry that concrete structures, such as foundations, require reinforcement means. Such reinforcement means typically are steel reinforcing bars or rods commonly known as “rebar”.
The general procedure followed for forming a concrete foundation includes building wood concrete forms, inserting rebar in the form of rods running the length of the foundation or in the form of a reinforcement cage into the forms, and pouring concrete into the forms.
A problem faced by concrete contractors is ensuring the anchor bolts are properly positioned and their position during creation of the foundation. Normally, a contractor uses a template or plastic bolt holding apparatus such as that disclosed in U.S. Pat. No. 6,065,730 attached to the concrete forms to hold the bolt in place while the concrete is poured, vibrated and set.
The present invention is directed to increasing the accuracy and performance of the placement of anchor bolts, mudsill anchors, or other construction connectors for wood studs or prefabricated structures, such as shearwalls, in foundations, and increasing the integrity of construction using such structures.